Thailand’s army chief denied on Friday that the military was about to stage a coup, as tensions rose ahead of protests for the third anniversary of a putsch that ousted former premier Thaksin Shinawatra, AFP reported.

Thousands of troops and police took up positions in Bangkok ahead of Saturday's rally by the pro-Thaksin 'Red Shirt' movement, which wants embattled current Prime Minister Abhisit Vejjajiva to step down and call elections.

Abhisit is heading to New York at the weekend for the UN General Assembly - and it was while billionaire Thaksin was out of the country to attend the same event that the military overthrew him in 2006.

“I can reassure everyone that there will be no coup. Absolutely no coup,” army chief General Anupong Paojinda told reporters. “To stage a coup is a big issue for the country and its repercussions would affect everybody. It's not something that anyone wants to do and it would not be in the interest of the country.”

The last time he denied that the army was about to intervene in politics was in December when the previous government, led by Thaksin's allies, was trying to end a blockade of Bangkok's airports by the royalist 'Yellow Shirt' group.

Gen Anupong, however, disobeyed government orders to crush the airport protests, and within days the fatally weakened administration had been toppled by a court ruling that cleared the way for Abhisit to come to power.

Abhisit's government itself is now on edge, caught in a rift with coalition partners over the choice of a new police chief and keen to avoid a repeat of angry Red Shirt protests in April which left two dead and scores injured.

Deputy Prime Minister Suthep Thaugsuban warned that if Saturday's protests become violent the government would impose emergency rule, as it did in Bangkok during the riots earlier this year. “If the normal law cannot cope and the situation is out of control, I will declare a state of emergency,” said Suthep, who will be acting prime minister in Abhisit's absence.

Dozens of soldiers armed with riot gear set up barbed wire and concrete blast walls on Friday outside Government House, where Abhisit's offices are located, AFP correspondents said. Others were posted outside the house of Prem Tinsulanonda, the chief advisor to Thailand's widely revered king. Prem is accused by the Red Shirts of masterminding the coup against Thaksin.

A total of more than 9,000 army, navy and air force personnel along with police would be mobilised for the coup anniversary protests, army spokesman Colonel Sunsern Kaewkumnerd told AFP.

Crowd control measures would start with negotiations, and then proceed to pushing back protesters, arresting leaders, using water cannon and tear gas and finally, shooting rubber bullets if necessary, he said.